Substantially hexane soluble propylene/butene-1 copolymer containing 30 to 75 weight percent butene-1

ABSTRACT

An amorphous propylene/butene-1 copolymer containing from about 30 to about 75 weight percent butene-1, and having a melt viscosity of about 100 to 100,000 centipoise at 190*C., a solubility in refluxing hexane of at least 99 weight percent, a solubility in refluxing diethyl ether of at least 60 weight percent, a ring and ball softening point in the range of about 78* to 120*C. and a Differential Scanning Calorimeter melting point not greater than 120*C.

United States Patent 11 1 Carter, Jr. et al.

[ Dec. 2, 1975 1 SUBSTANTIALLY HEXANE SOLUBLE PROPYLENE/BUTENE-lCOPOLYMER CONTAINING 30 T0 75 WEIGHT PERCENT BUTENE-l [75] Inventors:Edward H. Carter, Jr., Kingsport,

Tenn.; Robert E. Holliday, Longview, Tex.

[73] Assignee: Eastman Kodak Company,

Rochester, NY.

[22] Filed: July 2, 1973 [21] Appl. No.: 376,077

[52] US. Cl. 260/882; 260/93.7 [51] Int. CL C08F 10/06; COSF 10/08; C08F4/64 [58] Field of Search 260/882, 93.7

[56] References Cited UNITED STATES PATENTS 12/1959 Jezl 260/882 2/1972Hagemeyer et al. 260/878 B 3,644,309 2/1972 Duck et al. 260/80783,669,948 6/1972 Konotsune et al 260/937 3,679,775 7/1972 Hagemeyer etal. 260/878 B FOREIGN PATENTS OR APPLICATIONS 1,059,978 2/1967 UnitedKingdom 1,113,898 5/1968 United Kingdom Primary Examiner.loseph L.Schofer Assistant Examiner-A. L. Clingman [57] ABSTRACT 8 Claims, NoDrawings SUBSTANTIALLY HEXANE SOLUBLE PROPYLENE/BUTENE-l COPOLYMERCONTAINING 30 TO 75 WEIGHT PERCENT BUTENE-l This invention relates to anovel process for preparing propylene/butene-l copolymers and theproduct prepared thereby. More specifically, it relates to low molecularweight predominantly amorphous, hexane soluble propylene/butene-lcopolymers having a unique combination of properties. Another aspect ofthis invention relates to a novel high temperature polymerizationprocess for preparing these copolymers.

Previously, considerable work in the polymer art has been directedtowards the polymerization of propylene and higher olefins withstereospecific catalysts. The homopolymers and copolymers produced inthese polymerizations have found many uses, e.g., molded objects, film,coatings, sheeting and the like providing for a significant commercialsuccess for polypropylene and propylene/ethylene copolymers. However,due totheir high molecular weight and predominantly crystallinestructure the gross polymers prepared by such processes do not have thenecessary combination of properties for use in applications such as hotmelt adhesives and protective coatings. For example, to be useful in hotmelt adhesives a polymer must have, in addition to good adhesive andcohesive strength, a relatively low viscosity at moderate temperaturesand a constant melt viscosity-temperature relationship over a broadrange of temperatures to provide flexibility in both handling andapplication. In addition, the polymer should be predominantly amorphousto minimize the effects of crystallization on the adhesive and melt flowproperties.

None of the prior art propylene containing polymers from the crystallinepolymer. Furthermore, the molecular weight of the amorphous polymer isdifficult to control. These factors, due to their adverse effect on theeconomics of the process, severely limit the commercial utilization ofamorphous polypropylenes. Therefore, there is a need in the industry foran amorphous propylene based polymer that has the combination ofproperties required in hot melt adhesives and that can be prepareddirectly to the desired molecular weight in a commercially practicalprocess.

As previously pointed out, hexane soluble amorphous polypropyleneproduced as a by-product in the high temperature solution polymerizationof propylene with stereospecific catalysts is a useful hot meltadhesive. However, the amount of amorphous polypropylene which can beproduced by this method is controlled by the amount and crystallinity ofthe crude polypropylene produced. For example, the crude polypropyleneproduced with highly stereospecific catalysts, i.e., those containingtitanium trichlorides, contains at least weight percent crystalline(hexane insoluble) polymer and normally greater than percent. Thissituation severely limits the production of the amorphous component andhence the utilization of this material by industry.

Extensive experimentation has been conducted in an attempt to find atitanium based catalyst system and process conditions which result inthe synthesis of amorphous (hexane soluble) polypropylene withoutproducing crystalline polypropylene. In these experiments a number ofcatalyst systems were evaluated for synthesis of amorphous polypropyleneand amorphous propylene-ethylene copolymer. None of these systemsproduced a completely, i.e. at least 99 weight percent, amorphouspolymer. The properties of some of the polymers prepared in this studyare given in the following Table I.

Table I Propylene Polymers Physical Properties of the Polymers R848Soft. Catalyst System Monomers Pt. C. Hcxane Index. 71 Vise. at 190C,cp.

AlE -,/AA-TiCl Propylene 155 65.0 5,500 Et AlOEt/TiCl Propylene 155 28.35,200 EI AIOEt/TiCL, Propylene/Ethylene l27t) I42 l9.0 4.250 EtAlOEt/TiCl, Propylene/Ethylene 18%) l36 12.8 6.560 Et AlOEt/TiClPropylene/Ethylene (30%) 30.0 8,000 Allt;,/TiCl Propylene 25.0 5,000 EtAlOEt/AA-TiCl Propylene 152 35.0 4,500

Amount of polymer insoluble in hexane at 69C. -Ring and ball softeningtemperature, C. (ASTM E28-67). Solution polymerization at temperature ofC. and pressure of 1000 psig with hydrogen added to reduce molecularweight.

have the desired combination of properties for use as a hot meltadhesive with the exception of certain hexane soluble amorphouspolypropylenes. These amorphous polypropylenes are normally obtained asa by-product in the production of crystalline polypropylene by the hightemperature solution polymerization of propylene with stereospecificcatalysts. Although these amorphous polymers are useful in mayapplications, no method has been found for producing them directly andthey are always obtained either as a by-product or coproduct dependingon the process conditions and catalyst used in the polymerization. Thislack of a direct method of producing the amorphous polymer limitsproduction capacity and also necessitates an additional process step toseparate the amorphous polymer pletely hexane soluble propylene/butene-lcopolymers could be produced with an aluminum triethyl-titanium 3trichloride catalyst or an organopolylithiumaluminum compound-titaniumtrichloride catalyst at polymerization temperatures greater than 140C.

The reason for the complete hexane solubility and more random nature ofthe copolymers prepared by the process of this invention is not known.The reactivity ratios for propylene and butene-1 using an aluminumtriethyl/AA-titanium trichloride catalyst in our continuous hightemperature solution process were found to be r,(C,,l-l 1.60 and r (Cl-l,,) 0.52 which are essentially identical to the values reported inthe literature for this catalyst system. However, propylene/butene-lcopolymers prepared with the aluminum triethyl/AA-titanium trichloridecatalyst at temperatures below 140C. have higher ring and ball softeningpoints and higher hexane insoluble contents than copolymers made at hightemperatures. These results indicate that the copolymers made at hightemperatures contain more random propylene and butene-l segments thancopolymers made at lower temperatures. Since the a monomer reactivityratios are equivalent at both temperatures, this result was quiteunexpected. A possible explanation is that at high temperatures the rateof chain propagation in the copolymerization is considerable higher thanat the lower temperatures and as a result shorter and more randomsegments of propylene and butene-l are incorporated in the polymerchain.

In accordance with the present invention we have found that certaincopolymers of propylene and butene-l prepared as hereinafter described,have a combination of properties previously not available.

The composition and certain properties of the copolymers of thisinvention are listed in Table 11.

Table II Butene-l Content, wt. 71"" 30-75 Propylene Content. wt. 7125-66 Melt Viscosity Range at 190C., cp. loo-100.000

Ring & Ball Softening Temp., C."" 78-120 Hexane lnsolublc Polymer, wt.71" 5 1 Ether Insoluble Polymer. wt. /r'" S 40 DSC Melting Point, C.""None above the ring and ball softening point Density. g/cc 0.84-0.87

""Determined from infrared spectrum on melt sample 2 mil thick.

"Detcrmined by ASTM Procedure E28-67.

"Detcrmined by extracting 5 gram sample in Soxhlet extractor with hexaneat boiling point (69C.) for 6 hours.

"Determined by extracting 5 gram sample with diethyl ether at boilingpoint (30C.) for 6 hours.

"Determined on Differential Scanning Calorimeter manufactured by Perkin-Elmer Company at a heating rate of Cl'minule.

The copolymers of this invention are prepared by polymerizing a mixtureof propylene and butene-l in a high temperature solution process in thepresence of certain stereospecific catalysts, as disclosed in US. Pat.No. 3,679,775 which disclosure is incorporated herein by reference.

The catalysts useful in preparing these copolymers are combinations ofaluminum trialkyls or organopolylithiumaluminum compounds and a titaniumtrichloride. Aluminum trialkyls wherein the alkyl radical contains 2 to8 carbon atoms can be used as one catalyst component with aluminumtriethyl being the preferred component. The organopolylithiumaluminumcompounds are prepared by reacting a lithium alkyl with an aluminumtrialkyl. Lithium alkyls which contain 2 to 8 carbon atoms can be used,with lithium butyl being the preferred component. Methods for thepreparation of the organopolylithiumaluminum 4 compounds are disclosedin US. Pat. No. 3,679,775, which disclosure is also incorporated hereinby reference.

The titanium trichlorides useful as the second component of the catalystare hydrogen reduced titanium trichloride, activated by trituration(HA-TiCl aluminum reduced titanium trichloride, (ATiCl and aluminumreduced titanium trichloride activated by trituration (AATiCl Thepreferred form is AA- TiCl The hydrogen reduced titanium trichloride(HTiCl is not useful as the second component.

A mole ratio of aluminum trialkyl to titanium trichloride of 0.1/1 to1.0/1 is satisfactory for preparing the amorphous copolymer with0.4-0.6/1 being the preferred mole ratios. When anorganopolylithiumaluminum compound is used, the mole ratios of lithiumto aluminum to titanium are 0.0l0.05/0.1l.0/l with 0.05/0.5/1 being thepreferred ratio.

The temperature of the polymerization is critical and must be at leastC. or above in order to produce the hexane soluble copolymers. Theuseful range of temperatures is 140 to 250C. with the preferred rangebeing to 200C. Although temperature has a specific effect on themolecular weight, melt viscosity, of the copolymer produced, the primarymethod of controlling melt viscosity is by the addition of hydrogen tothe reaction. The amount of hydrogen necessary to maintain the molecularweight in the desired range is from about 0.0002 weight percent to about0.020 weight percent based on the monomers added to the reaction.

A suitable pressure range for the process includes, for example,pressures from atmospheric to about 2,000 atmospheres or more.Generally, it is preferred to use pressures in the range of about 1,000to 1,500 psig.

The organic solvents useful as the reaction medium include, for example,aliphatic alkanes or cycloalkanes such as propane, pentane, hexane,heptane, cyclohexane, and the like, or hydrogenated aromatic compoundssuch as tetrahydronaphthalene or decahydronaphthalene, or an aromatichydrocarbon such as benzene, toluene, xylene, and the like. The natureof the solvent is subject to considerable variation but should be in aliquid form at the reaction conditions and essentially inert to thereactants and reaction products. A petroleum fraction of suitableboiling range such as odorless mineral spirits (a sulfuric acid washedparaffinic hydrocarbon boiling at l80-220C.) is a particularly good andpreferred reaction medium. The amount of solvent necessary will dependon the viscosity of the copolymer being produced. For example, whencopolymers having a viscosity at C. of less than about 5,000 centipoiseare being produced only minor amounts of solvent, i.e., less than 10weight percent, are necessary. It should also be noted that thepolymerization can be carried out without solvent if the viscosity ofthe amorphous copolymer produced is low enough.

As previously noted, the copolymers of this invention are prepared in acontinuous solution process at high temperature. Although hexane solublecopolymers can be prepared in a batch solution process at hightemperature, a less random copolymer at a given butene-l content isobtained than in a continuous process. For example, a propylene/butene-lcopolymer containing 40 weight percent butene-l and having a meltviscosity of 3,500 centipoise at 190C. prepared according to thisinvention in a continuous process has a ring and ball softening point of103C. and an ether insoluble both the entire range of butene-1 contentsand melt viscosities and the preferred ranges.

content of 22 weight percent, whereas a propylene/butene-l copolymerhaving the same butene-l content and melt viscosity prepared underidentical conditions with the exception that the process is batch ratherthan continuous has a ring and ball softening point of 1 13C. and anether insoluble content of 28 weight percent.

The butene-l content and melt viscosity desired in a particularcopolymer will depend on the end use and is controlled by varying thesynthesis conditions. As pointed out in Table 11, the butene l contentcan vary from 30 to 75 weight percent with the preferred range being 40to 60 weight percent. A copolymer containing 30 weight percent butene-lis obtained by adding to the reactor weight percent butene-l. Atbutene-l contents below 30 weight percent the hexane solubility of thecopolymer decreases rapidly. As the butene-l content approaches 75weight percent the ring and ball softening point and strength of thecopolymers become too low to be of practical use.

The melt viscosity (centipoise at 190C.) of the co polymers can varyfrom 100 to 100,000 and is controlled primarily by the amount ofhydrogen added to the polymerization reaction and to a lesser degree bythe reaction temperature. The preferred range of melt viscosities foruse as hot melt adhesives and coatings is 1,50030,000 centipoise andmore preferably 3,000-5.000 centipoise. For other applications such asfree films and blends with other polyolefins, melt viscosities above10,000 are desirable.

Typical process conditions for producing the copoly- 50 mers of thisinvention in a continuous process are listed in Table [1. Catalyst,monomer, solvent, and hydrogen feed rates are for a 6.7 gallon closedloop continuous stirred reactor. Conditions are listed for production ofThis invention can be further illustrated by the following examples ofpreferred embodiments thereof, although it will be understood that theseexamples are included merely for purposes of illustration and are notintended to limit the scope of the invention unless otherwisespecifically indicated.

EXAMPLES 1-8 Propylene and butene-l were continuously polymerized in thepresence of mineral spirits, an aluminum triethyl/AA-titaniumtrichloride catalyst, and hydrogen. The polymerization was carried outin a jacketed 6.7 gallon closed loop stirred reactor equipped such thatcatalyst, solvent, butene-l propylene, and hydrogen could be meteredinto the reactor continuously in measured amounts. The copolymersolution was continuously removed from the reactor, passed through afilter and an alumina bed to remove the catalyst residues. and then thecopolymer was recovered by stripping away the mineral spirits with hotnitrogen. During the polymerizations the reactor temperature wasmaintained at l170C. and the reactor pressure was controlled at 1,000psi. The catalyst was comprised of aluminum triethyl AA-titaniumtrichloride at an aluminum/titanium mole ratio of 0.5/ 1. The catalystwas premixed in a nitrogen dry box in mineral spirits at roomtemperature in the order of addition AA-titanium trichloride andaluminum triethyl at a concentration of 0.05 pound catalyst per gallon.The operating conditions for producing propylene/butene-l copolymerscontaining 30-75 percent butene-l at viscosities from 1,500 to 30,000centipoise at 190C. and ring and ball softening points 80-120C. aregiven in Table III. Included in these tables are the physical propertiesof the copolymers produced and their paper-to-paper (40 pounds per reamKraft) adhesive properties.

Table III Amorphous PropylcnclButenc-l Copolymers Example No. l 2 3 4 56 7 8 Physical Properties Melt Viscosity at 190C.. Cp. 3.200 3 680 3.5003.900 3 400 3.100 3.300 30.000 Ring & Ball Softening PL. C. 1 15 113Butenc-l Content. 7( 69 58 53 49 43 38 34 45 Hexane (69C.) lnsol. Po1.,"/1 0.1 0.1 01 01 0 1 0.5 1 0 0.1 Ether (30C.) lnsol. Pol.. 7: a 5 l1 l518 22 26 32 25 Glass Trans. Temperature. C. ..20 l8 l6 l3 14 12 11 13Density. gJCC. 0.85 0.85 0.86 0.86 0 86 0 8 0.88 0.87 Pen. Hardness. mmI4 13 9 l0 8 6 4 6 Table Ill-continued Amorphous PropylenclButcnc-lCopolymcrs Example No. I 2 3 4 5 6 7 8 Adhesive Properties 2" Pop-Open.F. 120 I35 I40 150 180 185 190 224 73F. Peel Strength. g. (24 hr.) 575530 540 600 505 550 450 967 Dclamination Time. min. at 120F. 40 41 35 309 3 1 60 Elev. Temperature Peel. F. 86 86 86 90 95 100 105 172 Elev.Temperature Shcar. F. 150 155 162 173 I84 '202 220 200 SynthesisConditions Reactor Type 6.7 gal. stirred loop -------p 6.7 gal. RcactorTemperature. C. 168-I72C. 162 Reactor Pressure. psi. 1.000 psi. Catalyst.A1Et /AA-TiCl,. Catalyst Mole Ratio (Al/Ti) .O.5/l -------o ReactorResidence Time. hr. 4.35 4.35 4.35 2.95 2.82 3.10 2.75 4.33Polymer/Catalyst Yield 650 755 1.300 733 905 1.200 1.400 1.135 MineralSpirits Feed. lb./hr. 0.55 0.65 0.40 0.86 0.90 0.82 0.74 0.43 CatalystFeed. 1b./hr. 0.0062 0.0057 0.0035 0.0075 0.0075 0.0044 0.0035 0.0037Propylene Feed. 1b./hr. 2.20 3.01 3.47 5.34 6.05 6.31 6.70 4.02 Butenc-lFeed. lb./hr. 4.43 3.66 3.37 4.55 4.10 3.84 3.50 2.70 Hydrogen Feed.lb./hr. X 0.85 0.93 3.4 5.6 5.6 6.0 6.2 None Reactor Solids. "/1 90-9590-95 90-95 90-95 90-95 90-95 90-95 90-95 Propylene Conversion. /r 71.070.0 72.4 62.5 73 68.2 63.0 67 Butcne-1 Conversion. "/1 62.4 61.2 60.548.5 60 50.4 47.4 56 Production Ratc. lb./hr./gal. 0.58 0.64 0.68 0.811.0 0.89 1.1 0.63 Process Continuous EXAMPLE 9 Using the process asdescribed in Examples l-8, amorphous propylene/butene-l copolymer wasprepared with a melt viscosity at 190C. of 3,500 centipoise and a ringand ball softening point of 123C. which contained percent butene-l. Thiscopolymer shows a hexane (69C.) insoluble polymer content of 10 percent.

EXAMPLE 10 EXAMPLE 1 1 Using the process as described in Examples 1-8.amorphous propylene/butene-l copolymers were prepared with meltviscosities at 190C. of 3,0004,000 centipoise and ring and ballsoftening points of l06-130C. at reactor temperatures of 80. I00, 120,and 140C. The properties of the copolymers produced are given in TableIV.

like, as hot melt adhesives and coatings for substrates, such as paperboard, for example. Additives, stabilizers and the like can also beadded to the copolymer or copolymer containing blend. The amorphouscopolymer can also be modified by reaction with maleic anhydride to forma maleated copolymer. The amorphous copolymer can also be chlorinated.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

We claim:

1. A solution process for preparing an amorphous propylene/butene-lcopolymer which comprises contacting a mixture of propylene and butene-lsaid mixture containing about 30 to weight percent butene- I, with acatalyst mixture comprising a trialkyl aluminum or anorganopolylithiumaluminum compound and titanium trihalide of the groupconsisting of HA- TiCl ATiCl and AATiCl at a temperature of l400 to250C. and a pressure in the range of about atmospheric to about 2,000psig.

2. A solution process according to claim 1 wherein said trialkylaluminum is triethyl aluminum.

3. A solution process according to claim2 wherein said titaniumtrihalide is the AA form of titanium trichloride.

4. A solution process according to claim 3 wherein the ratio of triethylaluminum to the AA form of tita- Table IV Reactor Temperature. C. I20Melt Viscosity at C.. cp. 3.000 3.900 3.450 3.250 R 8; B SofteningPoint. C. 130 I25 120 I06 72 Butenc-l 56 46 48 5O HeXanC Index. 7( 13.412.5 10.6 1.0

The amorphous substantially hexane soluble propylene/butene-l copolymercontaining 30 to 75 weight percent butene-l can be used alone or inblends with other polymers such as polyethylene. polypropylene and thenium trichloride is 0.01-1.0/1.

5. A solution process according to claim 4 wherein the ratio of triethylaluminum to the AA form of titanium trichloride is 0.4-0.6/1.

3,923,758 9 10 6. A solution process according to claim 1 wherein ride-I I action product of lithium butyl and methyl aluminum. titaniumtrichloride is 7. A solution process according to claim 6 wherein 5 saidactivated titanium trihalide is the HA form of titanium trichloride orthe AA form of titanium trichlo-

1. A solution process for preparing an amorphous propylene/butene-1copolymer which comprises contacting a mixture of propylene andbutene-1, said mixture containing about 30 to 75 weight percentbutene-1, with a catalyst mixture comprising a trialkyl aluminum or anorganopolylithiumaluminum compound and titanium trihalide of the groupconsisting of HA-TiCl3, A-TiCl3 and AA-TiCl3 at a temperature of 140*0to 250*C. and a pressure in the range of about atmospheric to about2,000 psig.
 2. A SOLUTION PROCESS ACCORDING TO CLAIM I WHEREIN SAIDTRIALKYL ALUMINUM IS TRIETHYL ALUMINUM.
 3. A solution process accordingto claim 2 wherein said titanium trihalide is the AA form of titaniumtrichloride.
 4. A solution process according to claim 3 wherein theratio of triethyl aluminum to the AA form of titanium trichloride is0.01-1.0/1.
 5. A solution process according to claim 4 wherein the ratioof triethyl aluminum to the AA form of titanium trichloride is0.4-0.6/1.
 6. A solution process according to claim 1 wherein saidorganopolylithiumaluminum compound is the reaction product of lithiumbutyl and triethyl aluminum.
 7. A solution process according to claim 6wherein said activated titanium trihalide is the HA form of titaniumtrichloride or the AA form of titanium trichloride.
 8. A solutionprocess according to claim 7 wherein the mole ratio of lithium butyl totriethyl aluminum to titanium trichloride is 0.01-0.05/0.1-1.0/1.